1. Field of the Invention
The present invention relates generally to a wastewater clarificant comprising an aqueous solution containing a polynuclear complex salt of sulfates of a plurality of metals, and more specifically to a wastewater clarificant that can easily reduce chemical oxygen demand (COD for short), biochemical oxygen demand (BOD) and suspended solids (SS) components in wastewater with an improved efficiency.
2. Description of the Prior Art
Conventional wastewater or clarification or disposal treatments have been chiefly achieved by adding flocculants to wastewaters for removal-by-sedimentation of contaminants. Well-used flocculants, for instance, are aluminum sulfate, aluminum chloride, polyaluminum chloride, ferric chloride, ferrous sulfate and polyferric sulfate.
For the treatments of wastewaters discharged from various plants such as those for processing foodstuffs, marine products and livestock products, dyeing materials and making paper, inorganic flocculants such as aluminum sulfate, aluminum chloride, polyaluminum chloride, ferric chloride and polyferric sulfate have been widely used.
For the treatments of wastewaters of high turbidity, the flocculants mentioned above may be used in combination with high-molecular flocculants such as anions and cations to improve the efficiency of flocculation. Biological disposal systems are often used, although this depends on what types of wastewaters are treated.
For treating wastewaters discharged from plants for farming marine products such as eel and fish, aeration systems are always used for making up for dissolved oxygen (DO for short).
A grave problem with these wastewater disposal techniques is that it is impossible to provide easy yet well-efficient reductions in COD, BOD and SS in wastewaters. A problem with using high-molecular flocculants such as anions and cations as clarificants is that they are harmful to the human body and water containing them, even if purified, cannot be recycled as drinkable water. Of wastewater clarificants, the above-mentioned chlorine compounds are now used in large amounts, but they form free chlorine that is a substance harmful to the human body.
Severe problems with using the wastewater clarificants based on chlorine compounds are that they form toxic chlorine compounds such as dioxin--that is detected from fishes and sludge in sea areas in which pulp effluents flow, causing environmental pollution or destruction. For instance, chlorination of indoor pools incurs an increase in atopic diseases and reddish hair, gives rise to the occurrence of trihalomethane in the presence of humic acid or causes other health hazards. On the other hand, governments and municipal corporations now place environmental integrity and hygiene under stricter control than ever before.